Electrostatic air cleaner

ABSTRACT

An electrostatic air cleaner having a deenergizing or grounding device operative upon opening of a closure member to ground electrical components within the cleaner cabinet. The device includes at least two spaced contacts and a bridging element. One of the contacts is connected to ground and the other to a component within the cabinet. A spring biases the bridging element toward engagement with both contacts. An operator connected to the bridging element forces the bridging element out of engagement with the contacts when the closure member engages the operator upon closing of the closure member. The operator is resilient to compensate for variances but is less resilient than the spring so as to overcome the spring.

United States Patent [72] Inventor Donald M. Mullings Yardley, Pa. [21] Appl. No. 880,749 [22] Filed Nov. 28, 1969 [45] Patented Dec. 28, 1971 [73] Assignee General Electric Company [54] ELECTROSTATIC AIR CLEANER 1 Claim, 6 Drawing Figs.

[52] US. Cl SS/139, 55/140, 55/154, 200/16 A, ZOO/61.76 [5 l Int. Cl B03c 3/02 [50] Field of Search 55/139, 149, 154; 200/16 A,61.76

[ 56] References Cited I UNlTED STATES PATENTS 2,470,701 5/1949 Jacobs ZOO/61.78 2,693,510 11/1954 Luebking et a1. ZOO/61.76 X 2,722,574 11/1955 Simmons 200/16 A 2,822,450 2/1958 Goudy et a1. ZOO/l6 A X 2,899,511 8/1959 Fraser 200/16 A X 2,900,042 8/1959 Coolidge, Jr. et a1. 55/147 X 2/1960 Burch .l 200/16AX 3,064,104 Wells et al.

Primary Examiner Dennis E. Talbert, .lr. Attorneys-James E. Espe, Harry F. Manbeck, .lr., Frank L.

Neuhauser, Oscar B. Waddell and Joseph 'B. Forman ABSTRACT: An electrostatic air cleaner having a deenergizing or grounding device operative upon opening of a closure member to ground electrical components within the cleaner cabinet. The device includes at least two spaced contacts and a bridging element. One of the contacts is connected to ground and the other to a component within the cabinet. A spring biases the bridging element toward engagement with both contacts. An operator connected to the bridging element forces the bridging element out of engagement with the contacts when the closure member engages the operator upon closing of the closure member. The operator is resilient to compensate for variances but is less resilient than the spring so as to overcome the spring.

PATENTED M628 I87]. 6

sum 1 OF 2 F'IGZ .INVENTOR. DONALD. M. MULLJNGS HIS ATTORNEY PATENTEU [H5828 19?! SHEET 2 OF 2 FIGG INVENTOR. DONALD M. MULLINGS BY g a v fATTORNEV This invention relates generally to electrostatic air Cleaners and, more specifically, to an improved means to deenergize or ground certain of the electrical components of the cleaner automatically upon opening of a closure member in the cleaner cabinet.

Electrostatic air cleaners-generally include an ionizing section which may consist of fine wires located between plates. A voltage in the magnitude of 5,000 to 10,000 volts DC isimposed on the wires to charge any particles passing through the electrostatic field thus created. Down stream of the ionizing section is attracted to and collected on the plates.

It is necessary to periodically remove and clean the collecting plates and an access opening in the cleaner cabinet is provided for this purpose. A closure member is provided to normally close the access opening. The electrical charges established in the ionizing and collecting sections will remain for a substantial time afier the cleaner has been deenergized. The unit thus acts as a capacitor, storing the electrical charge. Unless the high voltage elements or components are grounded, the person cleaning the collective plates may receive a surprising, but nonlethal, shock from touching open contacts or the high voltage components when attempting to remove the plates for cleaning. Accordingly, it would be advantageous to provide means to deenergize or ground the high voltage elements of the air cleanerautomatically upon opening of the closure members. However, in many air cleaners there is very little space available in which to provide such means. The high voltages involved 'I'nay arc across a small air gap so that a conventional switch means may experience areing which will interfere with normal operation of the cleaner. Thus, it would also be advantageous to provide an improved means to deen'ergize or ground the high voltage elements which will operate satisfactorily in a limited, confined space.

It is, therefore, an object of this invention to provide an improved meansto deenergize or ground certain components of an electrostatic air cleaner automatically upon opening of its closure memberwhich will operate satisfactorily in a limited, confined space.

SUMMARY OF THE INVENTION Briefly stated, in accordance'w'ith one aspect of the present invention, there is provided an improved 'deenergizing or grounding device for the electrical components of an electrostatic air cleaner. The means is operable upon opening of a closure member providing access to the cabinet of the cleaner.

move the bridging'element from its first operative position to its second operative position upon closing of the closure member. The operator has a resiliency less than the resiliency of the biasing means so that the operator will overcome the force of the biasing means to maintain the bridging element in its second operative position when the closure member is closed.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification-concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention,-it is believed the invention will be better understood from the following description of the preferred embodiment taken in connection with the accompanying drawings, inwhich:

FIG. l'is a perspective view of an electrostatic air cleaner employing the present invention;

FIG. 2 is a fragmentary plan view of a portion of the present invention; I

FIG. 3 is a fragmentary exploded view of the electrical components and closure member of the air cleaner of FIG. 1;

FIG. 4 is a fragmentary sectional view of the switch means of the present invention in one operative position as seen along line 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 4 showing the switch means in another operative position; and,

FIG. 6 is a schematic diagram of the electrical circuitry of the air cleaner.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now :Jth drawings, there is illustrated an electrostatic air cleaner 10 having an outer cabinet 11 and a closure member 12 which allows access to the interior of cabinet 11 when opened. A manually operable handle 13 operates a latching mechanism which secures closure member 12 in its closed position and, upon rotation, unlatches to allow the opening of closure member 12. In accordance with conventional practice, cabinet 11 is adapted to be mounted in an air duct (not shown) such that the air passing through the duct must pass through cabinet 11 so that the electrical components therein may effect a cleaning action on the air. Cabinet 11 is provided with a flange 14 on one side thereof to which the duct is connected. It is to be understood that there is a similar flange on the opposite side of cabinet 11 which cannot be seen in FIG. I.

The air to be cleaned passes through cleaner 10 In the direction indicated by arrow 15. The air first encounters an ionizing section 16 which comprises a plurality of alternating plates 17 and fine wires 18. Because the wires 18 are of such fine diameter, they are not illustrated in FIG. 1 but are shown schematically in FIG. 6. Structurally, there is one fine wire 18 member 12 has been opened or removed. A handle 21a Is provided to facilitate manual withdrawal of cell 20a from cabinet 1]. The dirt particles collected on the plates must be removed from the plate periodically in order to maintain the cleaning efficiency of the air cleaner. These plates and the intermediate air gaps act as a capacitor, storing the electrical charge applied thereto. As will be described in greater detail hereinafter, the present invention provides an improved means for automatically discharging these plates as closure member 12 is opened to provide access to the plates for cleanisa.. w H

Referring now .to FIG.' 6, there is illustrated a schematic electrical diagram of the electrical circuitry of air cleaner 10. Lines 22 and 23 are connected to a suitable source of electrical energy (not shown which could comprise normal household wiring of volts AC. The primary coil 24 of a transformer 25 is connected across lines 22 and 23 so that the household power is applied thereto. Transformer 25 also includes a core 26 and a secondary coil 27. Transformer 25 is a voltage step-up transformer providing approximately a 30 to l step-up of the voltage. Accordingly, if lines 22 and 23 are connected to the standard 110 volt household wiring, the output of secondary coil 27 is approximately 3,500 volts AC.

The output of transformer 25 is applied to a voltage doubling network comprising diodes 28 and 29 and capacitors 30 and 31. The voltage doubling network operates as follows: capacitor 3.] is charged to substantially the output voltage of transformer ZS-through diode 28 during the negative half cycle ofthe voltage of coil'2.7. During the positive half-cycle,

capacitor 31 and the output voltage of transformer 25 charge capacitor 30. At this time, a voltage of approximately twice the voltage of coil 27 will appear across terminals 32 and 33. Thus, the voltage at terminal 32 is approximately 7,000 volts. A voltage divider comprising resistors 34 and 35 is connected across terminals 32 and 33 to provide a reduced voltage of approximately 5,300 volts at terminal 36. Terminal 32 is directly electrically connected to a contact 37 while terminal 36 is directly electrically connected to a contact 38. The foregoing circuitry, i.e., transformer 25, the voltage doubling network, the voltage divider network, and contacts 37 and 38 being disposed for engagement with terminals 39 and 40 upon closing of the closure member. Terminal 39 is directly electrically connected to the individual wires of the ionizing section 16 so that these wires are at approximately 7,000 volts. Terminal 40 is directly electrically connected to plates 20 of collecting section 19 so that these plates are at a potential of approximately .5,300 volts. Plates [7 of ionizing section 16 and plates 21 of collecting section 19 are directly connected to ground and are thus maintained at ground potential.

It is to be understood that the circuitry described above is for illustrative purposes only and, as will become evident as this description proceeds, may be varied considerably without affecting the present invention. This circuitry does not constitute a part of the present invention and it is described and illustrated herein only for the purposes of providing a complete understanding as to be environment in which the present invention can be utilized.

As explained above, after the air cleaner has been operating, and the voltages described above have been impressed on the elements of the ionizing section and the collecting section, there is a tendency for these elements to maintain these charges after the circuit has been deenergized in a manner similar to that in which a capacitor maintains a charge. Because it is necessary to periodically remove and clean the plates of collecting section 19, it is desirable to provide means whereby these residual charges will automatically be dissipated as closure member 12 is opened by one attempting to clean the plates.

In accordance with the present invention, a grounding means 41 is provided to ground wires 18 and plates 20 automatically as closure member 12 is removed from cabinet 11. Grounding means 41 includes a switch means having a bridging element 42 and contacts 43, 44 and 45. Bridging element 42 comprises a circular metallic disc. As illustrated in FIG. 6, contact 43 is directly electrically connected to wires 18, contact 44 is directly electrically connected to ground, and contact 45 is directly electrically connected to plate 20. With this arrangement, as bridging element 42 engages contacts 43, 44 and 45, wires 18 and plate 20 are concurrently directly connected to ground thereby dissipating any residual charge on wire 18 and plate 20.

Referring now to FIGS. 2, 3, 4 and 5, it can be seen that cell 20a has a compartment 46 at one end defined by spaced walls 47 and 48. Wall 48 has an opening 49 therein and an electrically insulative member 50 overlying the opening and secured to wall 48. Similarly, wall 47 has an opening 51 with an insulative member 52 overlying the opening. Walls 47 and 48 are electrically conductive and, through cabinet 11, are electrically grounded. Contact 44 is connected to ground by means of a washer 48a which partially overlies, and touches, wall 48.

Bridging element 42 is disposed within compartment 46 and is positioned to concurrently engage contacts 43, 44 and 45. Bridging element 42 is supported by a biasing means or coiled compression spring 53 which'in turn is supported by insulative member 52 through a bolt 54. Spring 53 urges bridging element 42 toward engagement with contacts 43, 44 and 45. A resilient operator 55, in the form of a coiled compression spring, is secured at one end to bridging element 42 and extends through an opening 56 in insulative member 50. The distal, or free, end of operator 55 is adapted to be engaged by closure member 12 and closure member 12 is secured to cabinet 11 in its closedposition. Because the resiliency, or

spring constant, of operator 55 is greater than that of spring 53, operator 55 will overcome the biasing force of spring 53 to move bridging element 42 out of engagement with contacts 43, 44 and 45 as illustrated in FIG. 5.

Operator 55 could be constructed from a rigid element such as a solid rod; however, by giving operator 55 a resilient construction, compensation is provided for tolerance variances between closure member 12 and bridging element 42 without overstressing spring 53 or creating interference between bridging element 42 and insulative member 42 as closure member 12 is closed.

II will be appreciated that the overall dimensions of cell 20a are limited by such factors as a relatively confined space in which air cleaner 10 may have to be installed. Accordingly, compartment 46 is similarly limited in size. This results in a very limited distance which bridging element 42, or any other movable contact, can move upon disengagement from contacts 43, 44 and 45. As mentioned above, relatively high voltages are being switched by grounding means 41, i.e., in the magnitude of 7,000 and 5,000 volts. Accordingly, with a normal switching means wherein a single movable contact and a single stationary contact were employed, the effective gap between contacts may be insufficient to prevent arcing during normal operation of the cleaner due to the high voltages involved. It is to be noted that the present invention, in effect, provides two airgaps between the voltage at wire 18 and ground and two airgaps between the voltage at plate 20 and ground. ln other words, in order for arcing to occur, an arc must be established from contact 43 to bridging element 42 and from bridging element 42 to contact 44. Similarly, an arc must be established from contact 45 to bridging element 42 and from bridging element 42 to contact 44. Thus, the grounding means of the present invention provides an effective airgap of almost twice the linear distance which would be provided by a conventional switch mechanism utilizing a single stationary contact and a single movable contact. Moreover, it should be noted that contacts 40, 43 and 44 form an arcuate pattern, i.e., they lie on a circle approximately defined by the periphery of bridging element 42. in this fashion, the distance between adjacent contacts is greater than if they were in a straight line thus increasing the distance that any arc must travel.

It should now be apparent that the present invention provides an improvedmeans to deenergize or ground certain components of an electrostatic air cleaner automatically upon opening of its closure member and one which operates satisfactorily in a limited confined space.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the example illustrated, and it is contemplated that various other modifications or applications will occur to those skilled in the art. It is, therefore, intended that the appended claims cover such modifications and applications as do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electrostatic air cleaner having a cabinet, electrical components within the cabinet and a closure member for the cabinet, grounding means to connect at least some of said electrical components to ground upon opening of said closure member, said means comprising:

at least two spaced contacts, one of which is electrically connected to at least one of said electrical components and the other of which is directly electrically connected to ground;

an electrically conductive bridging element having a first operative position and a second operative position, said bridging element engaging both of said contacts in said first operative position and being spaced from both of said contacts in said second operative position;

biasing means to bias said bridgin'g'element toward said first operative position; and

second operative position when said closure member is closed,

said biasing means being a coiled compression spring,

said resilient operator being a coiled compression spring,

and

said bridging element comprising a circular metallic disc carried by said biasing means. 

1. In an electrostatic air cleaner having a cabinet, electrical components within the cabinet and a closure member for the cabinet, grounding means to connect at least some of said electrical components to ground upon opening of said closure member, said means comprising: at least two spaced contacts, one of which is electrically connected to at least one of said electrical components and the other of which is directly electrically connected to ground; an electrically conductive bridging element having a first operative position and a second operative position, said bridging element engaging both of said contacts in said first operative position and being spaced from both of said contacts in said second operative position; biasing means to bias said bridging element toward said first operative position; and a resilient operator connected to said bridging element and adapted to be engaged by said closure member when said closure member is closed and move said bridging element from said first operative position to said second operative position; said operator having a resiliency greater than said biasing means whereby said operator overcomes the force of said biasing means to maintain said bridging element in said second operative position when said closure member is closed, said biasing means being a coiled compression spring, said resilient operator being a coiled compression spring, and said bridging element comprising a circular metallic disc carried by said biasing means. 